1 files changed, 78 insertions, 6 deletions

diff --git a/activesupport/lib/active_support/notifications/instrumenter.rb b/activesupport/lib/active_support/notifications/instrumenter.rb
index e99f5ee688..a03e7e483e 100644
--- a/activesupport/lib/active_support/notifications/instrumenter.rb
+++ b/activesupport/lib/active_support/notifications/instrumenter.rb
@@ -13,14 +13,15 @@ module ActiveSupport
         @notifier = notifier
       end
 
-      # Instrument the given block by measuring the time taken to execute it
-      # and publish it. Notice that events get sent even if an error occurs
-      # in the passed-in block.
+      # Given a block, instrument it by measuring the time taken to execute
+      # and publish it. Without a block, simply send a message via the
+      # notifier. Notice that events get sent even if an error occurs in the
+      # passed-in block.
       def instrument(name, payload = {})
         # some of the listeners might have state
         listeners_state = start name, payload
         begin
-          yield payload
+          yield payload if block_given?
         rescue Exception => e
           payload[:exception] = [e.class.name, e.message]
           payload[:exception_object] = e
@@ -52,8 +53,13 @@ module ActiveSupport
     end
 
     class Event
-      attr_reader :name, :time, :transaction_id, :payload, :children
-      attr_accessor :end
+      attr_reader :name, :time, :end, :transaction_id, :payload, :children
+
+      def self.clock_gettime_supported? # :nodoc:
+        defined?(Process::CLOCK_PROCESS_CPUTIME_ID) &&
+          !Gem.win_platform?
+      end
+      private_class_method :clock_gettime_supported?
 
       def initialize(name, start, ending, transaction_id, payload)
         @name           = name
@@ -63,6 +69,47 @@ module ActiveSupport
         @end            = ending
         @children       = []
         @duration       = nil
+        @cpu_time_start = nil
+        @cpu_time_finish = nil
+        @allocation_count_start = 0
+        @allocation_count_finish = 0
+      end
+
+      # Record information at the time this event starts
+      def start!
+        @time = now
+        @cpu_time_start = now_cpu
+        @allocation_count_start = now_allocations
+      end
+
+      # Record information at the time this event finishes
+      def finish!
+        @cpu_time_finish = now_cpu
+        @end = now
+        @allocation_count_finish = now_allocations
+      end
+
+      def end=(ending)
+        ActiveSupport::Deprecation.deprecation_warning(:end=, :finish!)
+        @end = ending
+      end
+
+      # Returns the CPU time (in milliseconds) passed since the call to
+      # +start!+ and the call to +finish!+
+      def cpu_time
+        (@cpu_time_finish - @cpu_time_start) * 1000
+      end
+
+      # Returns the idle time time (in milliseconds) passed since the call to
+      # +start!+ and the call to +finish!+
+      def idle_time
+        duration - cpu_time
+      end
+
+      # Returns the number of allocations made since the call to +start!+ and
+      # the call to +finish!+
+      def allocations
+        @allocation_count_finish - @allocation_count_start
       end
 
       # Returns the difference in milliseconds between when the execution of the
@@ -88,6 +135,31 @@ module ActiveSupport
       def parent_of?(event)
         @children.include? event
       end
+
+      private
+        def now
+          Concurrent.monotonic_time
+        end
+
+        if clock_gettime_supported?
+          def now_cpu
+            Process.clock_gettime(Process::CLOCK_PROCESS_CPUTIME_ID)
+          end
+        else
+          def now_cpu
+            0
+          end
+        end
+
+        if defined?(JRUBY_VERSION)
+          def now_allocations
+            0
+          end
+        else
+          def now_allocations
+            GC.stat :total_allocated_objects
+          end
+        end
     end
   end
 end